The `reader_consumer_v2` type
(`std::function<future<> (mutation_reader)>`) is defined alongside
`mutation_reader` in `mutation_reader.hh`.
before this change, we sometimes use
`std::function<future<> (mutation_reader)>` directly when defining a
consumer parameter or a consumer variable.
in this change, we improve maintainability by:
- Reducing duplicate function type declarations
- Centralizing the consumer type definition
- Making future signature updates easier to implement
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#21369
2498e37a2f